Populations evolve for many reasons. Suppose there is a population of plants that have either purple flowers or white flowers, and the allele for purple flowers is dominant. This means that plants with two purple alleles have purple flowers. Plants with one purple allele and one white allele also have purple flowers. Only plants with two white alleles have white flowers.
For each event or condition described below, answer the following questions.

Which mechanism of evolution is at work?
How does this event affect the population's gene pool? Do the frequencies of the two alleles change, and if so, how?
1. During an extreme heat wave, plants with white flowers survive better.

2. A person uproots the five closes plants, which all happen to have white flowers.

3. A storm kills many plants at random.

4. Plants with purple flowers attract more insects, which pollinates the plants.

5. Workers from a nearby greenhouse accidentally introduce white flower seeds into this population's habitat.